Barrio Logan supporters widened their appeal Friday to defeat a June 3 referendum on a new community plan, saying other neighborhoods could face similar challenges.

The plan and its implementing ordinances will appear as Propositions B and C on the upcoming citywide ballot as a result of a referendum drive mounted by the shipyard industry worried about expansion limitations and potential job losses.

At a press conference in La Jolla, Assembly Speaker Toni Atkins, D-San Diego, urged support of the plan, originally adopted by the City Council last fall, and spoke of a possible legislative fix to fend off similar challenges in the future.

"Proposition B and C may well be the most important decisions San Diegans will make about the future of their own communities for years to come," Atkins said.

A yes vote would keep the plan and ordinances in place; a no vote would repeal the plan and ordinances. They could not return for council reconsideration for at least a year unless there are substantial changes. The city spent five years and about $4 million to complete the plan.

Asked if she and other legislators might act to bar such challenges in future, she said, "I would not be surprised to see a legislator put something forward as a way to protect our communities."

Until now, plan supporters, led by the Environmental Health Coalition, have focused on the plan's benefits to improving neighborhood health and safety by rezoning industry and housing away from each other in certain sections of the 1,000-acre community southeast of downtown. They denied that jobs will be lost if the plan goes into effect.

Councilwoman Sherri Lightner, who represents La Jolla, said if B and C lose, a precedent might be set that would encourage opponents of community plans in other areas to take a similar route. As an example, she said developers might mount a referendum to stop residential land from being converted to open space use.

"By supporting the propositions, you are saying you stand with all neighborhoods in San Diego to respect and protect a public planning process in our city," Lightner said. "There is a lot here at stake with this arrogant challenge to our community planning process, to our most local and basic grass roots democracy."

Assemblywoman Lorena Gonzalez, D- San Diego, who represents the barrio, said if the plan loses, the neighborhood will continue the fight to improve local living conditions.

"We're going to continue to fight for our children," she said.

Retired Rear Admiral Len Hering, who has campaigned against the plan, said the plan supporters' new pitch amounted to "grasping at straws."

"They don't represent everybody in the community, not by a long shot," he said.

He said the final version of the barrio plan was the "worst" of those presented and political considerations drove its adoption.

Critics have said the plan's expansion of housing units sets up more industry conflicts, as well as posing problems for existing business expansion.